The present invention relates to steam reforming of hydrocarbons by contact with a supported nickel catalyst having improved activity and resistance to sulphur poisoning.
In particular, the invention is directed to an improved catalyst support material of high surface spinel, optionally promoted by Group III, IV or lanthanide metals. High surface spinel carrier materials provide a much improved sulphur resistance when employing hydrocarbon feedstock with high content of sulphur compounds due to a reduced degree of sulphur coverage on the carrier surface. Thereby, retaining sufficient catalytic activity with sulphur compounds containing feedstock.
The surface area of the carrier depends on the calcination temperature actually employed in the preparation of the carrier.
It has been found that spinel carrier material having a specific surface higher than or equal to a certain value after calcination at a predetermined calcination temperature posses the above advantageous properties.
Accordingly, the invention provides a process for catalytic steam reforming of a carbonaceous feedstock with improved resistance to sulphur poisoning and sintering characterised by contacting the feedstock with a nickel catalyst supported on magnesium aluminum spinel, MgO.xAl2O3, with a specific surface area, Asp[m2/g], higher than expressed by the formula Asp=400xc2x7exp(xe2x88x92Tc/400xc2x0 C.) obtained by calcination at a temperature Tc[xc2x0 C.] where Tcxe2x89xa7400xc2x0 C.
As mentioned herein before, steam reforming activity of the spinel supported nickel catalyst is further improved when promoting the catalysts by inclusion of additional metals.
Preferred metals are Zr, Y, W, La, Ce or a mixture of lanthanides including La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, commercially available as lanthanide concentrate. The above metal promoters are preferably included in the catalyst in a total amount of 0.01% to 10% by weight, most preferred in an amount of 0.5% to 5% by weight. The nickel content in the catalyst will be between 10% and 60% by weight, preferably between 15% and 40% by weight.
When operating the inventive process in industrial scale, it may be sufficient to arrange the above catalyst as top layer in a catalyst bed of a conventional nickel steam reforming catalyst.